From the perspective of industrial structure advancement and rationalization, this paper studied the impact of regional industrial structure upgrading on the economic growth of marine fisheries through theoretical analysis and empirical tests. The results show the effects of different industrial structure upgrading on the economic growth of marine fisheries is varied. The advancement evolution has a “suppression effect,” while rationalization evolution has a “promotion effect.” The adverse impact of advancement evolution is greater than the favorable impact of rationalization evolution. Therefore, the development of marine fisheries reduces this unfavorable impact from advancement evolution by accelerating the transformation of innovation-driven internal combustion and creating new kinetic energy and fostering new business forms; it is also necessary to coordinate regional structure upgrading and industrial internal structure adjustment, promote the effect of structural rationalization, strengthen internal and external linkages, and improve the overall effectiveness of marine fisheries.

The paper adopts the conventional data envelopment analysis (DEA) and bootstrap procedure to analyze the technical efficiency, while tobit regression is applied to identify the factors affecting efficiencies of exotic fish polyculture in Jammu and Kashmir (India). According to the statistical analysis of the variables utilized, there was a lot of variability in the inputs being used by the farmers, with the most variation being in the lime input. The DEA estimated technical efficiency for the sample farms in Jammu and Kashmir is 0.9771 and 0.9741, respectively, with least technical inefficiency of 3%. The bias-corrected (bootstrapped) technical efficiencies found were slightly lower than the ones estimated by conventional DEA. Mean allocative and cost efficiencies for sample farms in the Jammu region were 92% and 75%, respectively, and 84% and 74%, respectively, for farmers in the Kashmir region. Farming experience, age, and education have favorable impacts on technical efficiency of farmers in the state, but family size showed negative impacts. Efficiency improvement will eventually lead to increase in the production providing better scope for marketed surplus. More fisheries extension is suggested for expanding the exotic fish culture in the state making the enterprise a more profitable venture.

Improving total factor productivity (TFP) is the source of power for high-quality development. Industrial structure optimization is an important way to improve TFP. This paper constructed an econometric model of industry structure changes impacting on TFP in the marine fisheries and conducted an empirical test and analysis. The results showed that the industry rationalization, softening and processing coefficient of marine fishery had a significant “structural dividend” for improving its TFP; while the impact of industrial structure advancement and aquaculture-catching structure changes did not have “structural dividend”, but it could be a combination of other factors to reduce these adverse effects.We believe that simply pursuing the advanced evolution of the industrial structure is not conducive to sustainable development of fishery. Under the pursuit of the rationalization of the marine fishery industry structure, by promoting the coordinated evolution of marine fisheries advancement, aquaculture-catching structure and other factors, the "structural dividend" effect can be enhanced and the fishery can achieve sustainable development. Finally, it proposed to promote the development of advancement and rationalization of marine fishery industry structure coordinately, adjust fishery science and technology transformation direction and key points, and accelerate the development of intensive processing industry by cross-border integration.

Industrial structure adjustment is an important component of China’s supply-side structural reforms. This study examines the effect and action path of regional industrial structure transformation, through the lens of advancement and rationalization, on the economic fluctuation and quality of the marine fishery industry. The results show that regional industrial structure advancement (rationalization) promotes (reduces) economic fluctuation. Regarding the action paths, regional industrial structure advancement (rationalization) has a U-shaped (inverted U-shaped) relationship with economic quality. The regional industrial structure advancement level is greater than 5.108 in China’s coastal areas and on the right side of the U shape. Thus, the evolution of the industrial structure in these areas is conducive to improving the economic quality of marine fisheries. Meanwhile, The degree of regional industrial structure rationalization has not reached the optimum level, and most areas are far from optimum level. This suggests that the structural dividends from industrial structure rationalization not fully released and need further regulation. In terms of the overall effect, regional industrial structure transformation can cause economic fluctuations in marine fisheries, with the main force originating from industrial structure advancement. The path of regional industrial structure transformation affecting economic quality of marine fisheries is non-linear. At present, the industrial structure advancement transformation can improve economic quality, but the industrial structure rationalization needs to be further adjusted.

For China's fish and crustacean trade globally, the COVID-19 pandemic outbreak in 2020 has posed previously unprecedented challenges. This study investigates these concerns by analyzing China's fish and crustacean export activities and correlating the shift in trade throughout the pre-pandemic and pandemic phases. Despite the numerous factors for the changing trade, this research attempts to explain those related to the pandemic and coping mechanisms. The investigation is supported by and linked to a conceptual framework for the resilience of the perishable agricultural food system by China during the pandemic. The results indicated that fish and crustacean exports from China decreased as the incidence of infections increased both globally and within the country. Trade with important markets including Japan, Korea, and the United States was badly affected by the outbreak. While shipments to Korea saw the fastest growth throughout the pandemic, the monthly growth rate of fish exports to the USA was the lowest. However, China's fish and crustacean trade recovered well after the epidemic, with faster growth rates and lower instability. The pandemic even resulted in a decrease in the unit value realized for all fish and crustacean commodities. The government's long-term efforts to ensure food security and prompt policy responses during the outbreak have demonstrated that China's food system can endure and rebound from perturbations. China's “green route” for perishable agricultural goods in the domestic market and prohibition on illegal obstructions serve as examples of how to maintain supply flow during an outbreak.

The coordinated development of a complex system refers to the harmonious and coherent evolution of its subsystems. From the perspective of the coordinated development of ecological–economic–social complex systems, this paper analyzes the coordinated development mechanism (CDM) of the mariculture ecological–economic–social (MEES) complex system, constructs a coordinated development evaluation indicator system for the MEES complex system, and adopts the comprehensive evaluation model and the coupling coordination degree (CCD) model to empirically analyze the coordinated development level of the MEES complex system in China from 2009 to 2020. The results show that the comprehensive development level of China’s MEES complex system has improved significantly during this period, with the comprehensive development index increasing from 0.25 in 2009 to 0.76 in 2020, transitioning from a poor to an excellent status. Simultaneously, the CCD of the system increased progressively, experiencing phases of near dissonance, barely coupling coordination, primary coordination, and intermediate coordination, before finally reaching a stage of good coordination. Based on these findings, we further discuss and propose countermeasures to promote the coordinated development of China’s MEES complex system.